%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-7-6 on page II-199 in "Line breaking in inline formulas".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{163.0pt}

%StartShownPreambleCommands

%StopShownPreambleCommands

\begin{document}
Words before \mbox{$ \sum x_i = a + b $}  and after.

Words before ${ \sum x_i = a + b }$       and after.

Words before $ \sum x_i =\nobreak a +\nobreak b $
                                          and after.
\end{document}
